Oral supplements of vitamin D may boost production of protective compounds in the skin, and may ultimate help prevent skin infections, according to a new study.

The small study focused on patients with atopic dermatitis, characterised by areas of severe itching, redness and scaling, and found that supplements of vitamin D enhanced the skin’s ability to produce a peptide called cathelicidin, which protects against microbial invasion. The findings are reported in the Journal of Allergy & Clinical Immunology.

“[Our] results suggest that supplementation with oral vitamin D dramatically induces cathelicidin production in AD lesional skin, and may also induce production in normal skin,” wrote the researchers, led by Richard Gallo from the University of California, San Diego.

Atopic dermatitis (AD) is one of the first signs of allergy during the early days of life and is said to be due to delayed development of the immune system. According to the American Academy of Dermatologists, it affects between 10 to 20% of all infants, but almost half of these kids will 'grow out' of eczema between the ages of five and 15.

Study details

Gallo and his co-workers recruited 14 people with moderate to severe atopic dermatitis and 14 people with normal skin. All of the participants were given daily vitamin D supplements of 4000 IUs for 21 days. The researchers analyzed skin lesions at the start and end of the study, and levels of cathelicidin were determined.

After supplementation, the skin of people with AD showed statistically significant increases in cathelicidin from 3.53 to 23.91 relative copy units (RCU). Moreover, normal skin showed a “modest increase”, said the researchers, from 1.0 to 1.78 RCU. “These results suggest that supplementation with oral vitamin D dramatically induces cathelicidin production in the skin of patients with atopic dermatitis,” said co-researcher Tissa Hata. “It also slightly elevated its production in normal skin in this study.”

The researchers cautioned further research is needed to evaluate the long-term effects of vitamin D supplementation, and future studies should determine if this may be an adequate way to prevent infections in patients with atopic dermatitis.

Vitamin D

Vitamin D refers to two biologically inactive precursors--D3, also known as cholecalciferol, and D2, also known as ergocalciferol. Both D3 and D2 precursors are hydroxylated in the liver and kidneys to form 25- hydroxyvitamin D (25(OH)D), the non-active 'storage' form, and 1,25-dihydroxyvitamin D (1,25(OH)2D), the biologically active form that is tightly controlled by the body. The vitamin has been linked to an ever-increasing list of health benefits, ranging from protection against certain cancers to improved bone health, from protection against autoimmune diseases to a reduced risk of cardiovascular disease.